Methods for maintaining a filtering device within a lumen

ABSTRACT

In one embodiment of the present invention there is provided a method of filtering blood flow in a lumen by positioning an open loop filter support structure within a lumen; maintaining a position of the open loop filter support structure within the lumen using radial force generated by the open loop filter support structure; and filtering blood flow in the lumen using a filter supported by the open loop filter support structure. In one aspect, there is also applying radial force generated by the open loop filter support structure along the axial dimension of the lumen.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority as a continuation of U.S. patentapplication Ser. No. 12/862,694, filed Aug. 24, 2010, titled “METHODSFOR MAINTAINING A FILTERING DEVICE WITHIN A LUMEN,” now U.S. PatentPublication No. 2010-0324590-A1, which is a continuation of U.S. patentapplication Ser. No. 11/325,249, filed Jan. 3, 2006, titled “METHODS FORMAINTAINING A FILTERING DEVICE WITHIN A LUMEN,” now U.S. PatentPublication No. 2006-0241677-A1, now abandoned, which claims the benefitof U.S. Provisional Application No. 60/641,327, filed Jan. 3, 2005,titled “RETRIEVABLE INFERIOR VENA CAVA FILTER WIRE;” U.S. ProvisionalApplication No. 60/668,548, filed Apr. 4, 2005, titled “WEB-BASEDPULMONARY EMBOLI PROTECTION SYSTEM;” and U.S. Provisional ApplicationNo. 60/673,980, filed Apr. 21, 2005, titled “HELICAL EMBOLIC PROTECTIONDEVICE AND RETRIEVAL METHODS,” each of which are incorporated herein byreference in their entirety.

This application is related to the following patent applications: U.S.patent application Ser. No. 11/325,251, filed Jan. 3, 2006, titled“RETRIEVABLE ENDOLUMINAL FILTER,” now U.S. Patent Publication No.2006-0241678-A1, now abandoned; U.S. patent application Ser. No.11/325,611, filed Jan. 3, 2006, titled “COATED ENDOLUMINAL FILTER,” nowU.S. Pat. No. 7,785,343; U.S. patent application Ser. No. 11/325,230,filed Jan. 3, 2006, titled “ENDOLUMINAL FILTER,” now U.S. Pat. No.7,854,747; U.S. patent application Ser. No. 11/325,622, filed Jan. 3,2006, titled “ENDOLUMINAL FILTER,” now U.S. Patent Publication No.2008-0021497-A1, now abandoned; U.S. patent application Ser. No.11/325,229, filed Jan. 3, 2006, titled “SPIRAL SHAPED FILTER,” now U.S.Pat. No. 7,582,100; U.S. patent application Ser. No. 11/325,273, filedJan. 3, 2006, titled “FILTER DELIVERY METHODS,” now U.S. PatentPublication No. 2006-0241679-A1, now abandoned; U.S. patent applicationSer. No. 11/325,247, filed Jan. 3, 2006, titled “LUMEN FILTERINGMETHODS,” now U.S. Pat. No. 7,789,892; U.S. patent application Ser. No.11/969,827, filed Jan. 4, 2008, titled “ENDOLUMINAL FILTER WITHFIXATION,” now U.S. Patent Publication No. 2008-0147111-A1, nowabandoned; U.S. patent application Ser. No. 12/541,788, filed Aug. 14,2009, titled “SPIRAL SHAPED FILTER,” now U.S. Pat. No. 8,226,679;International Patent Application No. PCT/US2006/000087, filed Jan. 3,2006, titled “RETRIEVABLE ENDOLUMINAL FILTER,” now Publication No.WO2006/074163; and International Patent Application No.PCT/US2008/088606, filed Dec. 31, 2008, titled “ENDOLUMINAL FILTER WITHFIXATION,” now Publication No. WO2009/088905, each of the aboveapplications are incorporated herein by reference in their entirety.

BACKGROUND

1. Field of the Invention

This invention relates generally to devices and methods for providingfiltration of debris within a body lumen. More particularly, theinvention provides a retrievable filter placed percutaneously in thevasculature of a patient to prevent passage of emboli. Additionally,embodiments of the invention provide a filter that can be atraumaticallypositioned and subsequently removed percutaneously from a blood vesselusing either end of the filter.

2. Background of the Invention

Embolic protection is utilized throughout the vasculature to prevent thepotentially fatal passage of embolic material in the bloodstream tosmaller vessels where it can obstruct blood flow. The dislodgement ofembolic material is often associated with procedures which open bloodvessels to restore natural blood flow such as stenting, angioplasty,arthrectomy, endarterectomy or thrombectomy. Used as an adjunct to theseprocedures, embolic protection devices trap debris and provide a meansfor removal for the body.

One widely used embolic protection application is the placement offiltration means in the vena cava. Vena cava filters (VCF) prevent thepassage of thrombus from the deep veins of the legs into the bloodstream and ultimately to the lungs. This condition is known as deep veinthrombosis (DVT), which can cause a potentially fatal condition known aspulmonary embolism (PE).

The first surgical treatment for PE, performed by John Hunter in 1874,was femoral vein ligation. The next major advancement, introduced in the1950's, was the practice of compartmentalizing of the vena cava usingclips, suture or staples. While effective at preventing PE, thesemethods were associated with significant mortality and morbidity (see,e.g., Kinney TB, Update on inferior vena cava filters, JVIR 2003;14:425-440, incorporated herein by reference).

A major improvement in PE treatment, in which venous blood flow wasmaintained, was presented by DeWesse in 1955. This method was called the“harp-string” filter, as represented in FIG. 1A and FIG. 1B, in whichstrands of silk suture 12 were sewn across the vena cava 11 in atangential plane below the renal veins 13 to trap thrombus. Reportedclinical results demonstrated the effectiveness of this method inpreventing PE and maintaining caval patency. (see, e.g., DeWeese M S, Avena cava filter for the prevention of pulmonary embolism, Arch of Surg1963; 86:852-868, incorporated herein by reference). Operative mortalityassociated with all of these surgical treatments remained high andtherefore limited their applicability.

The current generation of inferior vena cava (IVC) filters began in 1967with the introduction of the Mobin-Uddin umbrella 21 (FIG. 1C) which isdescribed in further detail in U.S. Pat. No. 3,540,431. The Greenfieldfilter (FIG. 1D) was introduced in 1973 and is described in furtherdetail in U.S. Pat. No. 3,952,747. These conical-shaped devices wereplaced endoluminaly in the IVC and utilized hooks or barbs 20, 30 topierce the IVC wall and fix the position of the device. A variety ofconical-shaped, percutaneously placed vena cava filters, based upon thisconcept are now available. For example, the TULIP with a filterstructure 41 (FIG. 1E) further described in U.S. Pat. No. 5,133,733; theRECOVERY with a filter structure 51 (FIG. 1F) further described in U.S.Pat. No. 6,258,026; and the TRAPESE with a filter structure 61 (FIG. 1G)further described in U.S. Pat. No. 6,443,972.

The next advancement in filters added the element of recoverability.Retrievable filters were designed to allow removal from the patientsubsequent to initial placement. Retrievable filters are generallyeffective at preventing PE yet they have a number of shortcomings, suchas, for example: failure of the device to deploy into the vesselproperly, migration, perforation of the vessel wall, support structurefracture, retrievability actually limited to specific circumstances, andformation of thrombosis on or about the device.

Problems associated with retrievable, conical-shaped devices, such asthose illustrated in FIG. 1D, FIG. 1E and FIG. 1F, have been reported inthe medical literature. These reported problems include tilting whichmakes it difficult to recapture the device and compromises filtrationcapacity. Hooks 30, 40, 50, 60 used to secure these devices have beenreported to perforate the vessel wall, cause delivery complications, andfracture. A partially retrievable system is described in detail inpending U.S. Pat. No. 2004/0186512 (FIG. 1H). In this system, the filterportion 71 can be removed from the support structure 70, but the supportstructure remains in-vivo. All of these described devices share thecommon limitation that they can be retrieved from only one end. Each ofthe above referenced articles, patents and patent application areincorporated herein in its entirety.

In view of the many shortcomings and challenges that remain in the fieldof endoluminal filtering, there remains a need for improved retrievable,endoluminal filters.

SUMMARY OF THE DISCLOSURE

In one embodiment of the present invention there is provided a method offiltering blood flow in a lumen by positioning an open loop filtersupport structure within a lumen; maintaining a position of the openloop filter support structure within the lumen using radial forcegenerated by the open loop filter support structure; and filtering bloodflow in the lumen using a filter supported by the open loop filtersupport structure. In one aspect, In one embodiment of the presentinvention there is provided a maintaining a position of the open loopfilter support structure within the lumen is performed without piercingthe surface of the lumen. In one aspect, maintaining a position of theopen loop filter support structure within the lumen is performed withoutperforating the lumen.

In one aspect, there is also applying radial force generated by the openloop filter support structure along the axial dimension of the lumen. Inone aspect, maintaining a position of the open loop filter supportstructure within the lumen using radial force generated by the open loopfilter support structure positions the filter centrally within thelumen. In one aspect, there is also applying radial force generated bythe open loop filter support structure around the axial dimension of thelumen. In one aspect, there is also maintaining a nearly constantfiltering capacity of the filter supported by the open loop filtersupport structure as the size of the lumen changes. In one aspect, thereis also maintaining the filtering capacity of the filter supported bythe open loop filter support structure over a physiological range oflumen sizes. In one aspect, there is also maintaining the filteringcapacity of the filter supported by the open loop filter supportstructure independent of the size of the lumen.

In another embodiment of the present invention there is provided amethod of providing a filter across a lumen flow path by providing afilter support structure having a first end, a crossover section, and asecond end; and fixing the position of the filter support structurewithin the lumen by positioning the first end against a first portion ofthe lumen and positioning the second end against a second portion of thelumen; and using the filter support structure to provide a filter acrossthe lumen flow path. In one aspect, the ends do not pierce the lumensurface.

In one aspect, fixing the position of the filter support structurecomprises fixing the position of the filter support structure within thelumen by positioning the first end against a first portion of the lumenand positioning the second end against a second portion of the lumen andpositioning the crossover section against a portion of the lumen betweenthe first and second portions of the lumen. In one aspect, the portionof the lumen between the first and second portions of the lumen isopposite the first and second portions of the lumen. In one aspect,there is also provided another filter across the lumen flow path. In oneaspect, there is also a changing the distance between the crossoversection and the lumen wall opposite the crossover section in response tochanges in the lumen diameter. In one aspect, there is also a changingthe distance between the ends in response to changes in the lumendiameter. In one aspect, there is also delivering a pharmacologicalagent within the lumen using the filter support structure. In oneaspect, there is delivering a pharmacological agent within the lumenusing the filter.

BRIEF DESCRIPTION OF THE DRAWINGS

A better understanding of the features and advantages of embodiments ofthe present invention will be appreciated through reference to thefollowing detailed description that sets forth illustrative embodimentsand the accompanying drawings of which:

FIGS. 1A-1H illustrate various prior art filters;

FIGS. 2A-2C illustrate the response of a filtering device to changes inlumen size;

FIGS. 3-5 illustrate the interaction of a structural member with a lumenwall;

FIGS. 6A-8D illustrate various aspects of the structural members in afiltering device;

FIGS. 9A and 9B illustrate various aspects of a generally planer supportframe;

FIGS. 10A and 10B illustrate various aspects of a non-planer supportframe;

FIGS. 11-13C illustrate various aspects of and configurations formaterial capture structures;

FIGS. 14-14C illustrate various aspects of a filtering device havingthree support frames;

FIG. 15 illustrates planes of symmetry for filtering devices;

FIGS. 16A and 16B illustrate the response of a filtering device whencontacted by debris flowing in a lumen;

FIGS. 17-19 illustrate alternative filtering device aspects havingdifferent sized support frames and structural member lengths;

FIGS. 20-24 illustrate various alternative filtering device ends andstructural member joining techniques;

FIGS. 25-27C illustrate various alternative retrieval features;

FIGS. 28A-28C illustrate various techniques of joining or formingretrieval features;

FIG. 29 illustrates a filtering device with a retrieval featurepositioned within a lumen.

FIGS. 30-53D illustrate several alternatives techniques for joiningmaterial capture structures to support frames and forming filteringstructures;

FIGS. 54A-65F illustrate several alternative filtering structures;

FIGS. 66 and 67 illustrate various filtering device configurations;

FIGS. 68A-74D illustrate various techniques related to the delivery,recovery and repositioning of filtering devices;

FIGS. 75A-78F illustrate several exemplary methods of using a filteringdevice;

FIGS. 79-82 illustrate several alternative filtering deviceconfigurations adapted for the delivery of pharmacological agents; and

FIGS. 83A-87 illustrate several filtering device prototypes.

DETAILED DESCRIPTION

There remains a clinical need for improved endoluminal filter devicesand methods. Improved endoluminal filter devices provide effectivefiltration over a range of lumen sizes and are easy to deploy into andretrieve from a lumen. In addition, improved endoluminal filter devicesminimize thrombosis formation or tissue ingrowth on the device and areresistant to migration along the lumen. Improved endoluminal filterdevices also minimize device fatigue by eliminating barbs, hooks orother sharp curve design features that can produce stress points thatlead to fatigue. Embodiments of the filter devices of the presentinvention provide many and in some cases all of the features of improvedendoluminal filters and have a number of uses such but are not limitedto: embolic protection, thrombectomy, vessel occlusion, and tethered oruntethered distal protection.

Several embodiments of the present invention provide improved filtrationdevices that are durable, provide effective and nearly constant filtercapacity over a range of lumen sizes and are easily delivered andremoved from a lumen via either end of the device. Additionally,embodiments of the present invention can be delivered into and retrievedfrom a lumen using minimally invasive surgical techniques. One aspect ofan embodiment of the present invention is the construction of supportstructure elements using a shape memory material. The shape memorymaterial may have a pre-shaped form that ensures the support elementsare uniformly collapsible and, when deployed, provides a pre-definedrange of controllable force against the lumen wall without use of hooksor barbs.

The elongate support structure elements are configured to collapse andexpand with natural vessel movements while maintaining constantapposition with the vessel wall. One result is that the supportstructure shape and size track to vessel movements. As a result, thefilter density and capacity of embodiments of the present inventionremain relatively independent of changes in vessel size. Moreover, theself centering aspect of the support structure ensures the filtrationdevice provides uniform filtration across the vessel diameter. As such,embodiments of the present invention provide generally constantfiltration capacity of the device is maintained across the entire vessellumen and during vessel contractions and expansions.

Uniform filter capacity is a significant improvement over conventionaldevices. Conventional devices typically have a filter capacity thatvaries radially across a lumen. The radial variation in filter capacityusually results from the fact that conventional filtration elements havea generally wider spacing at the periphery of the lumen and closerspacing along the central lumen axis. The result is that larger embolican escape along the lumen periphery. During vessel expansions andcontractions, the radial variations in filter capacity are exacerbatedin conventional devices.

Another advantage of some embodiments of the present invention is thatwhen released from a constrained state (i.e., within a delivery sheath),the device assumes a pre-determined form with elongate support membersthat extend along and self center the device in the vessel. Theseelongate support members exert atruamatic radial force against thevessel wall to prevent or minimize device migration. Utilizing radialforce generated by the elongate support members obviates the need forhooks or barbs to secure the device within the vessel. As a result,embodiments of the present invention produce little or no damage to thevessel wall and lining while producing little or no systemic responsefrom the body. Additionally, when device retrieval is initiated, theuniformly collapsible form of the elongate support members causes theelongate support members to pull away from the vessel wall as the deviceis being re-sheathed. The movement of the elongate members away from thevessel wall facilitates the atraumatic removal of the device from thevessel wall.

Additional embodiments of the present invention may include a retrievalon one or both ends of the device. The use of retrieval features on bothends of the device allows deployment, repositioning and removal of thedevice to be accomplished from either end of the device. As a result,the use of retrieval features on both ends of the device enables bothantegrade or retrograde approaches to be used with a single device. Theretrieval feature may be integral to another structural member or aseparate component. In some embodiments, the retrieval feature iscollapsible and may have a curved shape or a generally sinusoidal shape.Additional aspects of retrieval features are described below.

General Principals and Construction

FIG. 2A illustrates an embodiment of a filtering device 100 of thepresent invention positioned within a lumen 10. The lumen 10 is cut awayto show the position of filter 100 deployed into within a lumen and incontact with the lumen wall. The filter 100 includes a first elongatemember 105 and a second elongate member 110. The elongate members arejoined to form ends 102, 104. The elongate members cross but are notjoined to one another at crossover 106. In one embodiment, the elongatemembers have first and second sections. First sections extend betweenthe end 102 and the crossover 106 and the second sections extend fromthe crossover 106 to the second end 104. While some embodiments contactthe lumen in different ways, the illustrated embodiment has the ends102, 104 against one side of the lumen interior wall while the crossover106 contacts the other side of the lumen interior wall with the elongatebodies in constant or nearly constant apposition along the lumeninterior wall between the ends 102, 104.

Material (i.e., thrombus, plaque and the like) flowing through the lumen10 of a size larger than the filtering size of the material capturestructure 115 is captured between or cut down by the filaments 118. Inthe illustrated embodiment of FIG. 2A, the material capture structure115 is supported by a rounded frame formed by the elongate members 105,110 formed between the end 102 and the crossover 106. Another roundedframe formed between the crossover 106 and the second end 104 and couldalso be used to support a material capture structure of the same ordifferent construction and filter capacity of the a material capturestructure 115. As such, a material removal structure supported by onerounded frame may be configured to remove material of a first size andthe material removal structure supported a the other rounded frame maybe configured to remove material of a second size. In one embodiment,the material removal structure in the upstream rounded frame removeslarger size debris than material removal structure in the downstreamrounded frame. Also illustrated in FIGS. 2A-2C is how the filter cells119 that make up the material capture structure is 115 maintain theirsize and shape relatively independent of movement of the first andsecond structural members 105, 110 over a physiological range of vesseldiameters.

FIGS. 2B and 2C illustrate how the elongate support structure elementsof embodiments of the present invention are configured to collapse andexpand with natural vessel movements while maintaining constantapposition with the vessel wall. FIGS. 2A, 2B and 2C also illustrate howdevices according to embodiments of the present invention are bothradially and axially elastic. In response to vessel size changes, ends102, 104 move out as the vessel size decreases (FIG. 2B) and then movein as the vessel size increases (FIG. 2C). In addition, the deviceheight “h” (measured from the lumen wall in contact with ends 102, 104to crossover) also changes. Device height “h” changes in direct relationto changes in vessel diameter (i.e., vessel diameter increases willincrease device height “h”). As such, device height (“h”) in FIG. 2C isgreater than device height (“h”) in FIG. 2A which is in turn greaterthan the device height (“h”) in FIG. 2B.

FIGS. 2A, 2B and 2C also illustrate how a single sized device can beused to accommodate three different lumen diameters. FIG. 2C illustratesa large lumen, FIG. 2A a medium sized lumen and FIG. 2B a small sizedlumen. As these figures make clear, one device can adapt to cover arange of vessel sizes. It is believed that only 3 device sizes areneeded to cover the range of human vena cava interior diameters thatrange from approximately 12-30 mm with an average interior diameter of20 mm. Also illustrated is the static or nearly static filter capacityof the material capture structure 115. In each different vessel size,the material capture structure 115, the filaments 118 and filter cell119 maintain the same or nearly the same shape and orientation withinthe support frame formed by the elongate bodies. These figures alsoillustrate the dynamic shape changing aspect of the device that may alsobe used to accommodate and conform to vessel irregularities, tortuosity,flares and tapers and while remaining in apposition to the wall. Becauseeach elongate body may move with a high degree of independence withrespect to the other, the loops or support frames formed by the elongatebodies can also independently match the shape/diameter of the lumensection in which it is placed.

FIGS. 3, 3A and 3B illustrate the device 100 deployed into the lumen 10.As illustrated in FIG. 3, the device 100 is oriented in the lumen withthe ends 102, 104 along one side of the interior vessel wall with thecrossover 106 on the opposite side. FIG. 3 illustrates an embodiment ofa device of the present invention that is shaped to fit within the lumen10 without distending the lumen. In FIG. 3A the elongate bodies 105, 110are in contact but are not joined at crossover 106. In FIG. 3B theelongate bodies 105, 110 cross one another at crossover 106 but areseparated (i.e., by a gap “g”).

FIGS. 4 and 5 illustrate how aspects of the device design can bemodified to increase the radial force applied against the interior wallof lumen 10. Devices having increased fixation force may be useful forsome applications, such as vessel occlusion or for distal protectionwhen a large amount of debris is expected. If a device is not intendedto be retrieved (i.e., permanently installed into a lumen) then highradial force design devices may be used to ensure the device remains inplace and distention may be used to trigger a systemic response (i.e., atissue growth response) in the lumen to ensure device ingrowth andincorporation with the lumen interior wall.

Filter device embodiments of the present invention having low oratraumatic radial force are particularly useful in retrievable devices.As used herein, atraumatic radial force refer to radial forces producedby a filtering device embodiment that meets one or more of thefollowing: radial forces high enough to hold the device in place withlittle or no migration and without damaging or overly distending thelumen interior wall; radial forces high enough to hold the device inplace but while triggering little or no systemic response for the vesselwall; or forces generated by device operation that trigger reducedsystemic response or a systemic response below that of a conventionalfilter.

In contrast to the device sized in FIG. 3 to minimize vessel distention,FIG. 4 illustrates a device 100 configured to exert greater radial forceto a degree to cause lumen wall to distend. FIGS. 4 and 5 illustratelumen wall distention by the end 102 (distention 10 b), by the crossover106 (distention 10 a), and by the end 104 (distention 10 c). Althoughnot shown in these figures, the elongate bodies would likely distend thelumen along their length as well.

The radial force of a device may be increased using a number of designfactors. Radial force may be increased by increasing the rigidity of theelongate body by, for example, using an elongate body with a largerdiameter. Radial force may also be increased when forming the shapes ofthe elongate bodies (i.e., during the heat treat/set processes forNitinol devices and the like), as well as in the material compostion andconfiguration.

Additional details of an embodiment of the support members 105, 110 maybe appreciated with reference to FIGS. 6A, 6B and 6C. FIGS. 6A, 6Billustrate the support members separately and then assembled together(FIG. 6C) about device axis 121. In general, the device axis 121 is thesame as the axis along the central of a lumen into which the device isdeployed. For purposes of illustration, the support members 105, 110will be described with reference to a sectioned lumen shown in phantomhaving a generally cylindrical shape. The support members may also bethought of as deployed within and/or extending along the surface of animaginary cylinder.

In the illustrative embodiments of FIGS. 6A, 6B and 6C, the supportmembers 105, 110 are shown in an expanded, pre-defined shape. In oneembodiment, the support members are formed from MRI compatiblematerials. The support members contain no sharp bends or angles toproduce stress risers that may lead to fatigue issues, vessel erosion,and facilitate device collapse. In some embodiments, each elongatemember is conventionally formed by constraining a shape memory materialsuch as a shape memory metal alloy or shape memory polymer on acylindrical shaping mandrel that contains pins to constrain the materialinto the desired shape. It should be noted that due to the low strainrates of the axial members during deployment, other flexible materialsand metals can be utilized. These include but are not limited toStainless Steel, various alloys, and some polymers such as PTFE,Polyamide, PEEK, etc. Thereafter, the material can be subjected to asuitable conventional heat treatment process to set the shape. One ormore planes of symmetry (i.e., FIG. 15) may be provided, for example, byforming both elongate members on a single mandrel and at the same time.Other conventional processing techniques may also be used to producesymmetrical filtering device embodiments. Additionally, retrievalfeatures described herein (if present) may be directly formed on thewire ends during support member processing. In addition, multipledevices, in a series on a long mandrel, can be made using these methods.

Examples of suitable shape memory alloy materials include, for example,copper-zinc-aluminium, copper-aluminum-nickel, and nickel-titanium (NiTior Nitinol) alloys. Nitinol support structures have been used toconstruct a number of working prototypes of filter devices of thepresent invention as well as for use in ongoing animal studies (seeexperimental results discussion below). Shape memory polymers may alsobe used to form components of the filter device embodiments of thepresent invention. In general, one component, oligo(e-caprolactone)dimethacrylate, furnishes the crystallizable “switching” segment thatdetermines both the temporary and permanent shape of the polymer. Byvarying the amount of the comonomer, n-butyl acrylate, in the polymernetwork, the cross-link density can be adjusted. In this way, themechanical strength and transition temperature of the polymers can betailored over a wide range. Additional details of shape memory polymersare described in U.S. Pat. No. 6,388,043 which is incorporated herein byreference in its entirety. In addition, shape memory polymers could bedesigned to degrade. Biodegradable shape memory polymers are describedin U.S. Pat. No. 6,160,084 which is incorporated herein by reference inits entirety.

It is believed that biodegradable polymers may also be suited to formcomponents of the filter device embodiments of the present invention.For example, polylactide (PLA), a biodegradable polymer, has been usedin a number of medical device applications including, for example,tissue screws, tacks, and suture anchors, as well as systems formeniscus and cartilage repair. A range of synthetic biodegradablepolymers are available, including, for example, polylactide (PLA),polyglycolide (PGA), poly(lactide-co-glycolide) (PLGA),poly(e-caprolactone), polydioxanone, polyanhydride, trimethylenecarbonate, poly(13-hydroxybutyrate), poly(g-ethyl glutamate), poly(DTHiminocarbonate), poly(bisphenol A iminocarbonate), poly(ortho ester),polycyanoacrylate, and polyphosphazene. Additionally, a number ofbiodegradable polymers derived from natural sources are available suchas modified polysaccharides (cellulose, chitin, dextran) or modifiedproteins (fibrin, casein). The most widely compounds in commercialapplications include PGA and PLA, followed by PLGA,poly(e-caprolactone), polydioxanone, trimethylene carbonate, andpolyanhydride.

While described as forming the support structures, it is to beappreciated that other portions of the filter device may also be formedfrom shape memory alloys, shape memory polymers or biodegradablepolymers. Other filter device components that may also be formed fromshape memory alloys, shape memory polymers or biodegradable polymersinclude, for example, all or a portion of a retrieval feature, amaterial capture structure or an attachment between a material capturestructure and a support structure.

FIG. 6A illustrates the first support member 105 extending from an end102 to an end 104 along in a clockwise manner about the lumen interiorwall (sectioned phantom lines) and the device axis 121. The supportmember 105 extends from the end 102 in section 1 at the 6 o'clockposition, up to the 9 o'clock position in section 2, the 12 o'clockposition in section 3, the 3 o'clock position in section 4 to the end104 at the 6 o'clock position in section 5. The support member 105 has atwo sections 120, 122 on either side of an inflection point 124. Theinflection point 124 is positioned at about the 12 o'clock position insection 3. The radius of curvature of the sections 120, 122 may be thesame or different. The cross section shape of the support member 105 isgenerally circular but may have one or more different cross sectionshapes in alternative embodiments.

FIG. 6B illustrates the second support member 105 extending from an end102′ to an end 104′ along in a counter-clockwise manner about the lumeninterior wall (sectioned phantom lines) and the device axis 121. Thesupport member 110 extends from the end 102′ in section 1 at the 6o'clock position, up to the 3 o'clock position in section 2, the 12o'clock position in section 3, 9 o'clock position in section 4 to theend 104′ at the 6 o'clock position in section 5. The support member 110has two sections 130, 132 on either side of an inflection point 134. Theinflection point 134 is positioned at about the 12 o'clock position insection 3. The radius of curvature of the sections 120, 122 may be thesame or different. The cross section shape of the support member 105 isgenerally circular but may have one or more different cross sectionshapes in alternative embodiments.

FIG. 6C illustrates the crossover 106 and first and second supportmembers 105, 110 joined together at the ends. The first sections 120,130 form a rounded frame 126. The angle β is formed by a portion of thelumen wall contacting end 102 and a plane containing the frame 126 andis referred to as the take off angle for the elongate members at end102. In one alternative, the angle β is formed by a portion of the lumenwall contacting end 102 and a plane containing all or a portion of oneor both sections 120, 130. In yet another alternative, the angle β isformed by a portion of the lumen wall contacting end 102 and a planecontaining all or a portion of end 102 and all or a portion of thecrossover 106. Another angle β is formed on end 104 as discussed abovebut in the context of end 104, a portion of the lumen wall contactingend 104, sections 122, 132 and the rounded frame 128 as illustrated inFIGS. 7A-7C. An angle formed by the support frames 126, 128 rangesgenerally between 20 degrees to 160 degrees in some embodiments andgenerally between 45 degrees to 120 degrees in some other embodiments.

FIG. 7A is a side view of section 130 in FIG. 6B, FIG. 7B is a top downview of FIG. 6B and FIG. 7C is side view of section 132 in FIG. 6B. Theangle β ranges generally between 20 degrees to 160 degrees in someembodiments and generally between 45 degrees to 120 degrees in someother embodiments. The angle α is formed by a portion of section 120, aportion of section 130 and the end 102. Alternatively, the angle α isformed by the end 102 and tangents formed with a portion of the sections120, 130. Another angle α is formed on end 104 as discussed above but inthe context of end 104, a portion of the lumen wall contacting end 104and sections 122, 132. The angle α ranges generally between 40 degreesto 170 degrees in some embodiments and generally between 70 degrees to140 degrees in some other embodiments.

FIG. 7D illustrates a top down view of FIG. 6C. The angle σ is definedas the angle between a portion of section 120 between the inflectionpoint 124 and the end 102 on one side and a portion of section 130between the inflection point 134 and the end 102′ on the other side. Theangle σ is also defined as the angle between a portion of section 122between the inflection point 124 and the end 104 on one side and aportion of section 132 between the inflection point 134 and the end 104′on the other side. The angle σ defined by sections 120, 130 may be thesame, larger, or smaller than the angle σ formed by the sections 122,132. The angle σ ranges generally between 10 degrees to 180 degrees insome embodiments and generally between 45 degrees to 160 degrees in someother embodiments.

FIG. 7D illustrates an end view of FIG. 6C taken from end 102. The angleθ is defined as the angle between a plane tangent to a portion ofsection 120 and a plane containing the end 102 that is also generallyparallel to the device axis 121. An angle θ may also be defined as theangle between a plane tangent to a portion of section 130 and a planecontaining the end 102 that is also generally parallel to the deviceaxis 121. The angle θ defined by section 120 may be the same, larger, orsmaller than the angle θ formed by the section 130. Similarly, an angleθ may be defined as discussed above and using as the angle between aplane tangent to a portion of section 122 or 132 and a plane containingthe end 102 that is also generally parallel to the device axis 121. Theangle θ ranges generally between 5 degrees to 70 degrees in someembodiments and generally between 20 degrees to 55 degrees in some otherembodiments.

FIGS. 7F and 7G are perspective views of an alternative embodiment ofthe device illustrated in FIG. 6C. In the embodiment illustrated inFIGS. 7F and 7G, the support member 110 crosses underneath and does notcontact the support member 105 at the crossover 106. The gap “g” betweenthe support members is also illustrated in the FIG. 7G.

FIG. 8A illustrates the elongate body 105 with a generally circularcross section. However, many other cross section shapes are possible andmay be used such as, for example, rectangular elongate body 105 a (FIG.8B), rectangular elongate body with rounded edges (not shown), ovalelongate body 105 b (FIG. 8C) and circular elongate body with aflattened edge 105 c (FIG. 8D). In some embodiments, an elongate bodywill have the same cross section along its length. In other embodiments,an elongate body will have different cross sections along its length. Inanother embodiment, an elongate body has a number of segments and eachsegment has a cross section shape. The segment cross section shapes maybe the same or different. The cross section shape of the elongate memberis a factor used to obtain the desired radial force along the elongatemember. The material used to form the elongate body (i.e., abiocompatible metal alloy such as Nitinol) may be drawn to have adesired cross section shape, or drawn in one cross section shape andthen treated using conventional techniques such as grinding, lasercutting and the like to obtain the cross section shape were desired.

FIGS. 9A, 9B illustrate an embodiment of a material capture structure115 extended across a generally planar, rounded frame 126 formed by thesupport members. FIG. 9A is a slight perspective view of a side view ofthe device. In this embodiment, sections 120, 130 of the support memberslie mostly within in a single plane (i.e., in a side view of FIG. 9Asection 110 is visible and blocks view of section 120) that also holdsthe rounded frame 126. FIG. 9B is a perspective view showing thematerial capture structure 115 extended between and attached to roundedframe 126. In this embodiment, the capture structure 115 extends acrossand is attached to the first sections 120, 130. In this embodiment, thematerial capture structure is a plurality of generally rectangularfilter cells 119 formed by intersecting filaments 118. Other types offilter structures are described in greater detail below and may also besupported by the support frames formed by the structural members. Insome embodiments such as FIGS. 9A and 9B, the angle β may also definethe angle between the device axis and a plane containing a materialcapture structure.

The support frame 126 and the material capture structure 115 is notlimited to planar configurations. Non-planar and compoundconfigurations, for example, are also possible as illustrated in FIGS.10A and 10B. FIG. 10A is a side view of a non-planar structural support110′ having another inflection point 134′ between the inflection point134 and the end 102. The structural support 110′ has more than onedifferent radius of curvature between the end 102 and the crossover 106.In some embodiments, there could be more than one radius of curvaturebetween the end 102 and the inflection point 134′ as well as be morethan one radius of curvature between the inflection point 134′ and theinflection point 134. As a result, section 130′ is a section possiblyhaving different shapes, a number of different curvatures and at leastone inflection point. As seen in FIG. 10B, the support structure 105′ isalso non-planar with more than one different radius of curvature betweenthe end 102 and the inflection point 124. In some embodiments, therecould be more than one radius of curvature between the end 102 and theinflection point 124′ as well as be more than one radius of curvaturebetween the inflection point 124′ and the inflection point 124. As aresult, section 120′ is a section having different shapes, a number ofdifferent curvatures and one or more inflection points. Similarnon-planar configurations may be used on end 104. The material capturestructure 115′ is adapted to conform to the shape of non-planar frame126′ to produce a non-planar filter support structure.

FIG. 11 illustrates a material capture structure 115 that remains in agenerally planar arrangement between opposing portions of the supportmembers 105, 110. In addition to FIG. 10B above, other alternativenon-planar capture structures are possible even if the support frame isgenerally planar. FIG. 12A is a perspective view of a non-planar capturestructure 245 within a generally planar support frame formed by supportmembers 105, 110. Capture structure 245 is formed by intersectingstrands, fibers, filaments or other suitable elongate material 218 toform filter cells 219. The capture structure 245 is slightly larger thanthe support frame dimensions resulting in a filter structure that isdeformed out of the plane formed by the support structure as illustratedin FIG. 12B.

The material capture structure 115 may be in any of a number ofdifferent positions and orientations. FIG. 13A illustrates an embodimentof a filter of the present invention having two open loop support framesformed by support members 105, 110. Flow within the lumen 10 isindicated by the arrow. In this embodiment, the material capturestructure 115 is placed in the upstream open loop support structure. Incontrast, the material capture structure may be positioned in thedownstream open loop support structure (FIG. 13B). In anotheralternative configuration, both the upstream and the downstream supportframes contain material capture structures 115. FIG. 13C alsoillustrates an embodiment where a material capture structure is placedin every support loop in the device.

There are filter device embodiments having equal numbers of supportframes with capture structures as support frames without capturestructures (e.g., FIGS. 13A and 13B). There are other embodiments havingmore support frames without capture structures than there are supportframes with capture structures. FIG. 14 illustrates a filter embodiment190 having more support frames without capture structures than supportframes with captures structures. The filter device 190 has two supportmembers 105, 110 that are positioned adjacent to one another to form aplurality of support frames that are presented to the flow within thelumen 10. Alternatively, the plurality of support frames positioned tosupport a material capture structure across the flow axis of the device190 or the lumen 10. The support members are joined together at end 192and have two inflection points before being joined at end 194. Thesupport members 105, 110 cross over one another at crossovers 106 and196. The support frame 191 is between end 192 and crossover 106. Thesupport frame 193 is between the crossovers 106, 196. The support frame195 is between the cross over 196 and the end 194.

In addition, the filter device 190 has a retrieval feature 140 on eachend. The retrieval feature 140 has a curved section 141 ending with aball 142. The retrieval feature 140 rises up above the lumen wallplacing the ball 142 and all or a portion of the curved section 141 intothe lumen flow path to simplify the process of snaring the device 190for retrieval or repositioning. Having a retrieval feature on each endof the device allows the device 190 to be recovered from the upstream ordownstream approach to the device in the lumen 10. Various aspects ofretrieval feature embodiments of the present invention are described ingreater detail below.

FIG. 14A illustrates the filter 190 imposed on a phantom cylinder having7 sections. The retrieval features 140 have been omitted for clarity.The first support member 105 extends clock wise from end 192 about andalong the axis of the device 121. The first support member 105 crossessection 2 at the 9 o'clock position, section 3 and the crossover 106 atthe 12 o'clock position, section 4 at the 3 o'clock position, section 5and the crossover 196 at the 6 o'clock position, section 6 at the 9o'clock position and section 7 and the end 194 at the 12 o'clockposition. The second support member 110 crosses section 2 at the 3o'clock position, section 3 and the crossover 106 at the 12 o'clockposition, section 4 at the 9 o'clock position, section 5 and thecrossover 196 at the 6 o'clock position, section 6 at the 3 o'clockposition and section 7 and the end 194 at the 12 o'clock position. FIG.14B illustrates an alternative device embodiment 190 a that is similarto the device 190 except that all support frames formed by the elongatemembers is used to support a material capture structure. In theillustrated embodiment, frames 191, 193 and 195 each support at materialcapture structure 115.

FIG. 14C illustrates an alternative configuration of filter 190. Thefilter device 190 b is similar to device 190 and 190 a and includes anadditional support member 198 extending along the support member 105. Inone embodiment, the additional support member 198 extends along thedevice axis 121, is positioned between the first and the second supportmembers 105, 110 and is attached to the first end 192 and the second end194. In the illustrative embodiment, the third support member 198 beginsat end 192 and the 6 o'clock position in section 1, crosses section 3and the crossover 106 at the 12 o'clock position, crosses section 5 andthe crossover 196 at the 6 o'clock position, and ends at the 12 o'clockposition in section 7 at the end 194.

FIG. 15 illustrates the planes of symmetry found in some filter deviceembodiments of the present invention. The filtering structure that wouldbe supported by one or both of the support frames is omitted forclarity. In one aspect, FIG. 15 illustrates an embodiment of anendoluminal filter of the present invention having a support structurethat is generally symmetrical about a plane 182 that is orthogonal tothe flow direction of the filter or filter axis 121 and contains acrossover point 106 between two structural elements of the supportstructure 105, 110. In another aspect, FIG. 15 illustrates an embodimentof an endoluminal filter of the present invention having a supportstructure that is generally symmetrical about a plane 184 that isparallel to the flow direction of the filter (i.e., axis 121) andcontains both ends of the support structure 102, 104. It is to beappreciated that some filter device embodiments of the present inventionmay have either or both of the above described symmetrical attributes.It is to be appreciated that the above described symmetrical attributesare also applicable to the construction of embodiments of the materialcapture structures alone or as installed in a filter.

FIGS. 16A and 16B illustrate the response of a filter device 200 inresponse to a piece of clot material 99 contacting the material capturestructure 115. The direction of flow and movement of the clot material99 within lumen 10 is indicated by the arrows. The filter device 200 issimilar to the embodiments described above with regard to FIGS. 6A-7Gwith the addition of the retrieval features 240 added to the ends 102,104. The retrieval feature 240 has a curved section with multiple curves141 that terminate with an atraumatic end 242. The multiple curves 141are advantageously configured to collapse about a retrieval device (i.e,a snare in FIGS. 71A, 71B) to facilitate device 100 capture duringretrieval. In this illustrative embodiment the multiple curves aregenerally shaped like a sinusoid and the end 242 is shaped like a ballor a rounded tip.

It is believed that upon embolic entrapment, the force fluid flow actingon clot material 99 is transmitted from the capture structure 115 tosupport frame 126 securing the capture structure 115. The force actingon the support frame 126 and in turn the support members 105, 110 urgesthe end 104 into the lumen wall. This action effectively fixes thesecond support frame 128. The force acting on the support frame 126causes the angle β associated with the support frame 126 to increase thesupport frame 126 wedges further into the lumen wall.

FIGS. 17, 18, and 19 illustrate various alternative filter deviceembodiments with support structures of different size and that may notbe in contact with the lumen wall. FIG. 17 illustrates a perspectiveview of a filter device 300 according to one embodiment of the presentinvention. In this embodiment, elongate members 305, 310 are joined atends 302, 304, to form frame 309 from end 302, sections 301, 303 andcrossover 306 and frame 311 from end 304, sections 307, 308 and crossover 306. The frame 309 supports another embodiment of a materialcapture according to the present invention. The illustrated materialcapture structure 312 includes a plurality of strands 313 joined 314 toform a plurality of filter cells 315. The strands 313 may be joinedusing processes described below (e.g., FIG. 53A-53D) or may be formed byextruding the desired shape and size filter cell 315 from a material(e.g., FIG. 56).

FIG. 17 illustrates a so-called capacitor design because the elongatemembers that form frame 311 are configured to expand and contract thesize and shape of frame 311 in response to changes in frame 309. Thisdesign feature allows an embodiment of the present invention toaccommodate a large range of sizing and diameter changes. FIG. 18illustrates an embodiment of the filter device 300 having a capturestructure 350 having filter cells 354 formed by intersecting strands352. FIG. 18 illustrates how inward movement of the frame 309 (indicatedby the arrows) is corresponds to outward movement (indicated by thearrows) in the frame 308.

FIG. 19 illustrates an alternative filter device embodiment where thesecond frame is not closed. The filter device 340 includes supportmembers 341, 343 that form a rounded support frame 344 to support thematerial capture device 115. The support members 341, 343 extend somedistance beyond the cross over 342 but are not joined to form anotherend. A portion 346 of the support member 343 is shown extending beyondthe cross over 342. The support members 341, 343 may extend for somedistance along the device axis after the cross over 342 and may followthe same or a different shape as the shape of the support members inframe 309. The support members may extend along the device axis similarto earlier described two loop embodiments but stop short of being joinedat a second end (e.g., FIG. 87).

The ends of the filter devices of the present invention may be formed ina number of ways. A portion of the support structures 105, 110 may bewound 180 around one another (FIG. 20). In the illustrated embodiment,the wound portion 180 is used to foam the end 102. In anotheralternative, the filtering device is foamed from a single support member105 that loops back on itself. In the illustrative embodiment of FIG.21, support member 105 is formed into loop 181 to form the end 102. Inan alternative to loop 181, the loop may contain a plurality ofundulations (i.e., loop 181 a in FIG. 22) or be formed into the shape ofa retrieval feature or other component of the filter device. In yetanother alternative, a cover is used to clamp, to join or otherwise bondthe structural members together. In the illustrative example of FIG. 23,a generally cylindrical cover 183 is used to join together members 105,110. The cover 183 may use any conventional joining method to secure thesupport members together such as adhesive, welding, crimping and thelike. An alternative tapered cover 185 is illustrated in the embodimentof FIG. 24. The tapered cover 185 has a cylindrical shape and a taperedend 186. The tapered end 186 around the end having the tapered cover 185and facilitates deployment and retrieval of the device. In oneembodiment, the cover 185 is made of the same material as the structuralmember and/or the retrieval feature.

Some filter device embodiments of the present invention may include oneor more retrieval features to assist recapturing and partially or fullyrecovering a deployed filter device. Retrieval features may be placed inany of a number of positions on the device depending upon the specificfilter device design. In one embodiment, the retrieval device ispositioned not only for ease of device recovery but also attached to thedevice in such a way that pulling on the retrieval device actuallyfacilities removal of the device. In one embodiment, pulling on theretrieval device pulls the structural members away from the lumen wall.These and other aspects of the cooperative operation of the retrievalfeatures during deployment and recapture will be described below withregard to FIGS. 72A-73D.

Several alternative embodiments of retrieval devices of the presentinvention are illustrated in FIGS. 25-27C. FIG. 25 illustrates aretrieval device 240 with a simple curve 241 formed in the end. FIG. 26illustrates a retrieval device 240 with a curve 244 that is has asharper radius of curvature than the curve 241 in FIG. 25. FIG. 27Aillustrates a retrieval feature 140 having a curved section 141 with anatraumatic end 142. In the illustrative embodiment, the atraumatic end142 is a ball than may be added to the end of curve 141 or formed on theend of the member used to form the feature 140. A ball 142 may be formedby exposing the end of the curved section 141 to a laser to melt the endinto a ball. FIG. 27B illustrates a retrieval feature with a pluralityof curved sections 241. In one embodiment, the curved sections 241 havea generally sinusoidal shape. In another embodiment, the curved sections241 are configured to collapse when pulled on by a retrieval device likea snare (i.e., FIGS. 71A, 71B) FIG. 27C illustrates a retrieval feature240 having a plurality of curved sections 241 and a ball 142 formed onthe end. In additional embodiments, retrieval features of the presentinvention may include markers or other features to help increase thevisibility or image quality of the filter device using medical imaging.In the illustrative embodiment of FIG. 27C, a radio opaque marker 248 isplaced on the curved section 241. The marker 248 may be made from anysuitable material such as platinum, tantalum or gold.

A cover placed about the ends may also be used to join a retrievalfeature to an end or two support members. A cover 183 may be used tojoin a retrieval feature 240 to a support member 105 (FIG. 28A). In thisillustrative embodiment, the support structure 105 and the retrievalfeature 240 are separate pieces. A cover 183 may also be used to jointogether two members 110, 105 to a retrieval feature 140 (FIG. 28B). Inanother alternative embodiment, the retrieval feature is formed from asupport member that is joined to the other support member. In theillustrative embodiment of FIG. 28C, the support member 105 extendsthrough the tapered cover 185 and is used to form a retrieval feature240. The tapered cover 185 is used to join the first support member andsecond support member 105, 110. In one alternative of the embodimentillustrated in FIG. 28C, the diameter of the support member 105 isgreater than the diameter of the retrieval feature 240. In anotherembodiment, the diameter of the retrieval feature 240 is less thandiameter of the support member 105 and is formed by processing the endof the support member down to a smaller diameter and is then shaped tofoam the retrieval feature 240. In another embodiment, the ball 242 orother atraumatic end is formed on the end of the retrieval feature.

FIG. 29 illustrates a partial side view of a filter device in a lumen10. This figure illustrates the retrieval feature angle τ formed by theretrieval feature and the interior lumen wall. The retrieval featureangle τ is useful in adjusting the height and orientation of theretrieval curves 214 and ball 242 within the lumen to improve theretrievably of the device. Generally, retrievably improves as theretrieval feature moves closer to the device axis 121 (i.e., central tothe lumen axis as well). Additional curves may be added to the supportmembers 110, 105 as needed to provide the desired range of retrievalfeature angles. In one embodiment, τ ranges from −20 degrees to 90degrees. In another embodiment, τ ranges from 0 degrees to 30 degrees.

Attachment of Material Capture and Other Filtering Structures to SupportStructures

A number of different techniques may be used to attach material capturestructures to support members. For clarity, the material capturestructure has been omitted from the illustrations that follow but wouldbe suitably secured using the line 351 or a loop. In FIG. 30 illustratesa line 351 with a number of turns 353 about a support member 105. Theline 351 is secured back onto itself using a clip 351 a. FIG. 31illustrates a line 351 with a number of turns 353 about the supportmember 105 to secure a loop 353 a that may be used to tie off orotherwise secure a material capture structure. A line 351 may also beglued 355 to a support 105 (FIG. 32). In another alternative embodiment,holes 356 formed in the support member are used to secure one or morelines 351 that are used in turn to secure a material capture structure.In an alternative to the linear arrangement of holes 356, FIG. 36illustrates how holes 356 may be provided in a number of differentorientations to assist in securing a material capture to the supportstructure 105. Alternatively, the line 351 may be glued 355 into thehole 356 (FIG. 34A and in section view 34B).

In other alternative embodiments, the holes 356 are used to secure lines351 as well as provide a cavity for another material to be incorporatedinto the support structure 105. Other materials that may be incorporatedinto the support structure 105 include, for example, a pharmacologicalagent or a radio opaque material. The use of a radio opaque marker maybe useful, for example, when the support structure is formed from amaterial with low imaging visibility such as, for example, shape memorypolymers or biodegradable polymers. FIG. 34C illustrates an embodimentwhere one hole 356 is used to secure a line 351 and the other is filledwith material or compound 357. In another alternative, some or all ofthe holes 356 may be filled with another material as in FIG. 35. In yetanother alternative, the holes 356 are filled with small barbs 358 thatmay be used to secure the device to the lumen wall. The illustrativeembodiment of FIG. 37 the barbs 358 are only long enough to break thesurface of the lumen interior wall and not pierce through the lumenwall. While each of the above has been described with regard to thesupport member 105, it is to be appreciated that these same techniquescould be applied to the support member 110 or other structure used tosupport a material capture structure.

It is to be appreciated that the support structure embodiments are notlimited to single member constructions. FIG. 38A illustrates analternative braided support member 105′. Braided support structure 105′is formed by 4 strands a, b, c, and d. FIG. 38B illustrates anotheralternative braided support member 105″. Braided support structure 105″is formed by 3 strands a, b, and c. FIG. 38B also illustrates how thebraid structure may be used to secure a line 351. As can be seen in thisembodiment, by using the line 351 a material capture structure (notshown) is secured to at least one strand within the braided structure105″.

FIGS. 39 and 40 illustrate additional alternative techniques to secure afilter support structure to a support member. As illustrated in FIG. 39,there is illustrated a technique to secure a material capture structuresecuring line 351 to a support frame 105 using a material 481 wrappedaround the support frame 105. In this manner, the material capturestructure (not shown but attached to the lines 351) is attached to amaterial 481 that at least partially covers the first support structure105. The lines 351 are passed between the material 481 and the supportstructure 105 as the material 481 as wraps 483 are formed along thesupport structure 105. The lines 351 are omitted in the embodimentillustrated in FIG. 40 as the material 481 forms wraps 483 and is usedto secure the material capture structure (not shown). In one embodiment,the material 481 forms a tissue ingrowth minimizing coating over atleast a portion of support structure. Alternatively, the filteringstructure (not shown) is attached to the support structure 105 using atissue ingrowth minimizing coating 481.

FIGS. 41, 42 and 43 relate to securing the material capture structure toa lumen disposed around the support member. FIG. 41 illustrates a lumen402 that has been cut into segments 402 a, 402 b, 402 c that are spacedby a distance “d.” Lines 351 are attached around the support member andin the space “d” between adjacent segments. The segments may remainapart or be pushed together to reduce or eliminated the spacing “d.” Incontrast the segments in FIG. 41, the lumen 402 in FIG. 42 providesnotches 403 for securing line 351. FIG. 43 illustrates a lumen 405having a tissue growth inhibiting feature 408 extending away from thesupport member 105. As seen in section view 406 the inhibiting feature408 has a different cross section shape than the support member 105. Inaddition, in some embodiments, the lumen 405 is selected from a suitabletissue ingrowth minimizing material so that is acts like a tissueingrowth minimizing coating on the support structure. In otherembodiments, the cross section shape 406 is configured to inhibit tissuegrowth over the tissue ingrowth minimizing coating.

FIGS. 44 and 45 illustrate filter device embodiments utilizing duallumen structures. The dual lumen structure 420 includes a lumen 422 anda lumen 424 and has a generally teardrop shaped cross section area. Inthis illustrative embodiment, the support structure 105 is disposed inthe lumen 422 and the second lumen 424 is used to hold lines 351 andsecure a material capture device (not shown). In the illustrativeembodiment, the lumen structure 420 has been cut to form a number ofsegments 420 a, b, c and d in the lumen 424. The connection rings formedby the segments 420 a-d are used to secure lines 351 as needed. FIG. 45illustrates an alternative configuration for the lumen structure 420. Inthis alternative configuration, a release line 430 extends through thenotched lumen 424. The lines 351 extend about the release line 430 andhence to secure the material capture structure (not shown). Since thelines 351 are connected using the release line, removal of the releaseline from lumen 424 will allow the material capture structure securedusing the lines 351 to be released from the support structure andremoved from the lumen. A configuration such as that shown in FIG. 45provides a filtering structure that would be releasably attached to anopen loop (i.e., an open loop frame formed by the support structure).The embodiment illustrated in FIG. 45 provides a release line 430positioned along the open loop (formed by member 105) and a filteringstructure (not shown) is attached to the open loop using the releaseline.

In another embodiment, a filter device of the present invention isconfigured to be a coated endoluminal filter. In addition to coating allor a portion of the support structures or filter elements of thisdevice, the coating on the support members may also be used to secure afiltering structure to the support structure. In one embodiment, acoated endoluminal filter has a support structure, a filtering structureattached to the support structure and a coating over at least a portionof support structure. In one aspect, the coated support structure mayform a rounded support frame, an open loop or other structure to supporta filtering structure described herein. In one embodiment, the coatingover at least a portion of support structure is used to secure aplurality of loops (i.e., flexible form or rigid form) to the supportstructure. The plurality of loops are then used to secure a filteringstructure such as a material capture structure, for example, within thecoated endoluminal filter. In one embodiment, the coating is a tissueingrowth minimizing coating.

It is to be appreciated that a filtering structure may also be attachedto the support structure using the tissue ingrowth minimizing coating.In some embodiments, the tissue ingrowth minimizing coating is wrappedaround the support structure or, alternatively, it may take the form ofa tube. If a tube is used, the tube may be a continuous tube or comprisea plurality of tube segments. The tube segments may be in contact orspaced apart. The tube may have the same or different cross sectionshape than the support member. In another embodiment, the tissueingrowth minimizing coating is in the shape of a tube and the supportstructure is in the interior of the tube.

In some other embodiments, a bonding material is provided between thetissue ingrowth minimizing coating and the support structure. Thebonding material may be wrapped around the support structure or may takethe form of a tube. If a tube is used, the tube may be a continuous tubeor comprise a plurality of tube segments. The tube segments may be incontact or spaced apart. The bonding material tube may have the same ordifferent cross section shape than the support member or the coatingabout the bonding material. In one embodiment, the bonding material isin the shape of a tube with the support member extending through thebonding material tube lumen. In one embodiment, a plurality of loops(i.e., flexible form or rigid form) are secured to the support structureby sandwiching the line used to form the loops between a bondingmaterial around the support member and a coating around the bondingmaterial. In one embodiment, the bonding material has a lower reflowtemperature than the coating around the boding material. In thisembodiment, the line used to form the loops is secured at least in partby reflowing the bonding material to secure the line between the coatingaround the bonding material and the support structure. In anotheralternative, the coating around the bonding material is a shrink fitcoating that also shrinks around the bonding structure and the supportmember during or after a process that reflows the bonding material. Inany of the above alternatives, the plurality of loops may be used tosecure a filtering structure such as a material capture structure, forexample, within the coated endoluminal filter.

Some embodiments of the coated endoluminal filter include some or all ofthe other features described herein such as, for example, a retrievalfeature on the support structure, a retrieval feature on each end of thesupport structure, a support structure having two elongate bodies thatare joined together to form a rounded frame, and a support structurehaving two spiral shaped elongate bodies. In addition, some coatedendoluminal filters have a support structure that is generallysymmetrical about a plane that is orthogonal to the flow direction ofthe filter and contains a crossover point. In another alternative coatedendoluminal filter embodiment, the support structure of the coatedendoluminal filter is generally symmetrical about a plane that isparallel to the flow direction of the filter and contains both ends ofthe support structure.

FIGS. 46-51B illustrate several aspects of coated endoluminal filterembodiments. These figures are not to scale and have exaggerateddimensions to make clear certain details. FIG. 46 illustrates a numberof segments 450 of a coating placed about the support member 105. One ormore lines 451 extend between the segment 450 and the support member 105and form a plurality of loops 453. In one embodiment, the line 451 is asingle continuous line. Once formed, the segments 450 undergo suitableprocessing to shrink the segment diameter around the line 451 and thesupport member 105 thereby securing the line 451 and loops 453 againstthe support structure (FIG. 47). The segment 450 is secured about thesupport member 105 as illustrated in the end view of FIG. 51A. Thesegments 450 in the embodiment shown in FIG. 47 are spaced apart. Inother embodiments, the segments 450 may be in contact or have spacingdifferent from that illustrated in FIG. 47. The sizes of the variouscomponents illustrated in FIGS. 46, 47 and 51A are exaggerated to showdetail. The dimensions of one specific embodiment are: the supportmember 105 is a NiTi wire having an outside diameter of between 0.011″and 0.015″; the segments 450 are 0.2″ long cut from a PTFE heat-shrinktubing having and a pre-shrunk outside diameter of 0.018″ and a wallthickness of 0.002″; the line 451 is monofilament ePTFE of an outerdiameter of 0.003″ and the loops 453 have a nominal diameter of betweenabout 0.1″ to about 0.4″.

FIGS. 48, 49 and 51B illustrate a bonding material 456 about the supportmember 105 and a number of segments 455 about the bonding material 456.One or more lines 451 extend between the segments 455 and the bondingmaterial 456 and form a plurality of loops 453. In one embodiment, theline 451 is a single continuous line. Once formed, bonding material 456and/or the segments 450 undergo suitable processing to secure the line451 between the bonding material 456 and the coating 455 therebysecuring the line 451 and loops 453 against the support structure (FIG.49). The coating segment 450 and the bonding material 456 is securedabout the support member 105 as illustrated in the end view of FIG. 51B.The segments 455 in the embodiment shown in FIG. 48 are spaced apart byspacing “d.” In other embodiments, the segments 455 may be in contactafter processing (FIG. 49) or have spacing different from thatillustrated in FIG. 48. In a preferred embodiment, the spacing betweenthe segments 455 is removed by a portion of the boding material 456flowing between and securing adjacent segments 455. The sizes of thevarious components illustrated in FIGS. 48, 49 and 51B are exaggeratedto show detail. The dimensions of one specific embodiment are: thesupport member 105 is a NiTi wire having an outside diameter of between0.011″ and 0.015″; the segments 455 are 0.3″ long cut from a PTFEheat-shrink tubing having a pre-shrunk outside diameter of 0.022″ and awall thickness of 0.002″; the bonding material is a tube of FEP heatshrink tubing having a pre-shrunk outside diameter of 0.018″ and a wallthickness of 0.001″; line 451 is 0.002″ outer diameter PET monofilamentand the loops 453 have a nominal diameter of between about 0.1″ to about0.4″. It is to be appreciated that the segments 450, 455 and bondingmaterial 456 may be formed, for example, from: ePTFE, PTFe, PET, PVDF,PFA, FEP and other suitable polymers. Moreover, embodiments of strands,lines, fibers and filaments described herein may also be formed fromePTFE, PTFe, PET, PVDF, PFA, FEP and other suitable polymers.

FIG. 50 illustrates the use of a continuous flexible line 452 passedthrough a continuous coating segment 450 forming loops 454. The loops454 are disposed along the length of the coating 450 at regularintervals; the continuous coating segment 450 are uniform in length tothe support members 105 using a PTFE heat shrink tubing havingpre-shrunk diameter of 0.018″ and a wall thickness of 0.002″. The line452 is monofilament ePTFE of an outer diameter of 0.003″ and the loops454 have a nominal diameter of between about 0.1″ to about 0.4″.

FIGS. 52A-53D illustrate alternative techniques for forming and/orattaching a filtering structure to a support structure. FIG. 52Aillustrates an embodiment of a support frame 126 formed by supportmembers 105, 110 between the end 102 and crossover 106 as describedabove. Loops 453/454 are formed using lines 451/452 as described abovewith regard to FIGS. 46-51B. Thereafter, a filament 461 is suitablyattached 462 to a line 451/452 by tying, welding, gluing or byincorporating the filament 461 during the processing steps describedwith regard to FIGS. 46-51B. Next, the filament is traverses across theframe 126 and about the loops 453/454. In this embodiment, the lacingpattern between loops crosses a line extending between the end 102 andthe crossover 106. The general pattern is that the filament extendsacross the frame 126 and around one right side loop (1) and back acrossthe frame 126 (2) and around (3) a left side loop 453/454. The lacingprocess continues as shown in FIGS. 52B and 52C. When completed, thelacing process produces a filtering structure 465 from one or morefilaments secured to loops 451/452 that are secured to the supportmembers 105/110. The filament in the filtering structure 465 may be tautbetween the loops 451/452 or have some degree of sag (as illustrated inFIG. 52D). Filament 461 or other material used to form material capturestructure may be coated with a pharmacological agent (coating 466 inFIG. 58). The pharmacological agent may be any of a wide variety ofcompounds, drugs and the like useful in the procedures performed usingor the operation of various filtering device embodiments of the presentinvention. The pharmacological agent coating 466 may includepharmacological agents useful in preventing or reducing thrombusformation on the filtering structure, chemically lysing debris capturedin the filtering structure and the like.

FIG. 53A illustrates an embodiment of a support frame 126 formed bysupport members 105, 110 between the end 102 and crossover 106 asdescribed above. Loops 453/454 are formed using lines 451/452 asdescribed above with regard to FIGS. 46-51B. Thereafter, a filament 461is suitably joined 462 to a line 451/452 by tying, welding, gluing or byincorporating the filament 461 during the processing steps describedwith regard to FIGS. 46-51B. Next, the filament 461 was laced asdescribed above with regard to FIG. 52A about the loops 453/454. In thisembodiment, however, the lacing pattern between loops remains generallyparallel to a line extending between the end 102 and the crossover 106.When completed, the lacing process produces a filtering structure fromone or more filaments 461 that extend parallel to a line between the end102 and crossover 106 and are secured to loops 451/452 secured to thesupport members 105/110. This filtering structure (FIG. 53A) may be usedwithin a filter device of the present invention. In addition, thefiltering structure in FIG. 53A (as well as the structure in FIG. 52D)may be further processed to join 468 adjacent filaments 461 to formfilter cells 469 as part of a filtering structure 470. The process usedto join 468 adjacent filaments 461 may include any conventional joiningtechnique such as tying, welding, bonding, gluing, and the like. Inaddition, segments of tubing (i.e., segments 450, 455 456 describedabove) could be used to join 468 portions of adjacent filaments 461. Inone specific embodiment, the filament 461 is ePTFE monofilament with anouter diameter of 0.003″ joined 468 using a piece of FEP heat shrinktubing having a pre-shrunk outer diameter of 0.008″ and a wall thicknessof 0.001″. The filtering structure 470 may be taut between the loops451/452 or have some degree of sag (as illustrated in by the filteringstructure in FIG. 52D). The filter cells 469 may be formed in numeroussizes and shapes as described in greater detail below.

Alternatively, the filtering structures in FIG. 53A and FIG. 52D mayincorporate additional loops 491 formed by looping the filament 461 asillustrated in FIG. 57A.

Alternative Filtering and/or Material Capture Structures

In some embodiments, the material capture structure contains a number offilter cells. Filter cells may be formed in a number of different waysand have a number of different shapes and sizes. The shape, size andnumber of filter cells in a specific filter may be selected based on theuse of a particular filter. For example, a filter device of the presentinvention configured for distal protection may have a filter cell sizeon the order of tens to hundreds of microns to less than 5 millimetersformed by a selecting a filter material with a pore size (FIG. 63A, 63B)suited to the desired filtration level. In other applications, thefilter cell may be formed by overlapping (i.e., joined or crossedwithout joining) filaments to form cells that will filter out debris ina lumen above a size of 2 mm. Various other filter sizes and filtrationcapacities are possible as described herein.

Intersecting filaments (FIG. 54C) may be used to form diamond shapedfilter cells (FIG. 54A), as well as rectangular shaped filter cells(FIGS. 54B, 2A and 9B). Multiple strand patterns may also be used suchas the three strand 461 a, 461 b and 461 c array illustrated in FIG.57B. Intersecting filaments may also be knotted, tied or otherwisejoined 468 (FIGS. 55A and 55E). Intersecting filaments may form the sameor different filter cell shapes such as, for example, an elongated ovalin FIG. 55C, one or more joined diamonds as in FIG. 55B and an array ofjoined polygons as in FIG. 55D. Cells may also be formed using thetechniques described above in FIGS. 52A-53D. In one embodiment, a filtercell is defined by at least three intersecting filaments 461. The filterelement 461 may be formed from any of a wide variety of acceptablematerials that are biocompatible and will filter debris. For example,filaments, lines and strands described herein may be in the form of amultifilament suture, a monofilament suture a ribbon, a polymer strand,a metallic strand or a composite strand. Additionally, filaments, linesand strands described herein may be foamed from expandedpolytetrafluoroethylene (ePTFE), polytetrafluoroethylene (PTFe),Poly(ethylene terephthalate) (PET), Polyvinylidene fluoride (PVDF),tetrafluoroethylene-co-hexafluoropropylene (FEP), or poly(fluoroalkoxy)(PFA), other suitable medical grade polymers, other biocompatiblepolymers and the like.

The joined polygons may have any of the shapes illustrated in FIGS.60A-60F. It is to be appreciated that filter cells may have any, one ormore, or hybrid combinations of shapes such as, for example, circular(FIG. 60A), polygonal (FIG. 60B), oval (FIG. 60C), triangular (FIG.60D), trapezoidal or truncated conical (FIG. 60E).

In addition, the material capture structure may have filter cells formedby extruding a material into a material capture structure. FIG. 56illustrates an exemplary filtering structure 312 where a material isextruded into strands 313 that are joined 314 and spaced apart for formone of more filter cells 315. In one embodiment, the strands areextruded from Polypropylene material, forming diamond shaped filtercells approximately 4 mm in height and 3 mm in width.

FIGS. 59A-63B illustrate several different filtering structureconfigurations. For simplicity of illustration, the filtering materialis shown attached to a circular frame 501. It is to be appreciated thatthe circular frame 501 represents any of the various open loop, roundedframe or other support frames described herein. FIG. 59A illustrates aframe pattern similar to FIG. 52D. FIG. 59B adds an additionaltransverse filaments 461 a at an angle to the filaments 461. FIG. 59Cillustrates a plurality of filaments 461 a extending up from the framebottom 501 a about a central filament 461 c and a plurality of filaments461 b extending down from the frame top 501 b about a central filament461 c. In this illustrative embodiment, the filaments 461 a,b arearranged symmetrically about the central filament 461 c. Othernon-symmetrical configurations are possible. More than one centralfilament 461 c may be used to form a variety of different size andshaped polygonal filter cells (e.g., FIG. 59E).

Filaments may also be arranged using a variety of radial patterns. Frexample, multiple filaments 461 may from a common point 509 out the edgeof frame 501. In some embodiments, the common point is central to theframe 501 (FIG. 59D) and in other embodiments the common point 509 is ina different, non-central location. The sectors formed by the multiplefilaments (FIG. 59D) may be further divided into multiple filter cellsegments by winding a filament 461 a about and across segment filaments461 b. In contrast to a single filament spirally out from the point 509as in FIG. 59G, the segmented filter cells in FIG. 59F are formed byattaching single filament 461 a to the segment filaments 461 b.

FIGS. 61A-C and FIG. 62 illustrate the use of a sheet of material 520 toform a filter structure. The material 520 may have any of a variety ofshapes formed in it using any suitable process such as punching,piercing, laser cutting and the like. FIG. 61A illustrates a circularpattern 521 formed in material 520. FIG. 61B illustrates a rectangularpattern 523 formed in material 520. FIG. 61C illustrates a complexpattern 522 cut into material 522. It is to be appreciated that thematerial 520 may also be placed in the frame 501 without any pattern(FIG. 62). The illustrative embodiment of FIG. 62 may be useful foroccluding the flow within a lumen. Suitable materials 520 for anocclusion application include for example, wool, silk polymer sheets,other material suited to prevent blood flow in a lumen when extendedacross a lumen and the like. Additionally, the filter material 520 maybe a porous material having pores 530 (FIG. 63A). The material 520 maybe selected based on the average size of individual pores 530 (FIG. 63B)depending upon the procedure or use of the filter device. For example,the material 520 may be any of the porous materials using in existingdistal protection and embolic protection devices. In general, a widevariety of pore 530 sizes are available and may range from 0.010″ to0.3″. Other pore sizes are also available depending upon the material520 selected.

FIGS. 64-65F illustrate the use of nets or other web structures withinthe filtering device. The various net structure embodiments describedherein are used as material capture structures within filter deviceembodiments of the present invention. Each of these alternative isillustrated in a support structure similar to that of device 100 in FIG.2A and elsewhere. When deployed within the lumen 10, the materialcapture structure 560 has a defined shape such as a cone with a discreteapex 565 (FIG. 64A). In this embodiment, the net structure is longenough to contact the sidewall of the lumen 10 when deployed in thelumen 10. Alternatively, the apex 565 may be attached to the end 104 tokeep the net 560 in the lumen flow path and out of contact with thelumen sidewall (FIG. 64B). The net 565 may also have a rounded apex 565(FIG. 65A) or a truncated cone (flat bottom) (FIG. 65D). Alternatively,the net 560 may a discrete apex 565 so short that it will not contactthe lumen sidewall when deployed (FIG. 65B). The short net may also havea rounded apex 565 (FIG. 65B), a flat apex (FIG. 65E) or a sharp apex(FIG. 65C). In addition, the net 560 may have a compound apex 565 (FIG.65F).

FIGS. 66 and 67 illustrate how various different features describedabove can be combined. For example, FIG. 66 illustrates a multi-supportframe device 480 having a retrieval feature on only one end and an openframe (i.e., no filter structure). FIG. 67 illustrates an alternativemulti-support frame device 485 having different retrieval features oneach end, filter structures in each of the support structures and eachof the filter structures having a different filter capacity. It is to beappreciated that the above described details of the construction,components, sizes, and other details of the various filter deviceembodiments described herein may be combined in a number of differentways to produce a wide array of alternative filter device embodiments.

Delivery, Recovery and Repositioning of a Filtering Device

FIG. 68A illustrates an embodiment of the filter device 100 of thepresent invention loaded into an intravascular delivery sheath 705. Thedevice 100 is illustrated and described above, for example, in relationto FIG. 16A. Using conventional endoluminal and minimally invasivesurgical techniques, the device can be loaded into the proximal end ofthe sheath 705, before or after advancing the sheath 705 into thevasculature, and then advanced through the sheath using a conventionalpush rod. The push rod is used to advance the device 100 through thedelivery sheath lumen as well as fix the position of the device(relative to the sheath 705) for device deployment. In one preferredtechnique, the device is loaded into the proximal end of a deliverysheath that has already been advanced into a desired position within thevasculature (FIG. 68B). The device 100 may be pre-loaded into a shortsegment of polymeric tubing or other suitable cartridge that allows thedevice 100 to be more readily advanced through a hemostasis valve.

When used with a compliant delivery sheath 705, the pre-formed shape ofthe device 100 deforms the sheath to conform to the device shape (FIG.69A, 69B). Accordingly, a flexible, compliant sheath 705 assumes thecurvature of the stowed device. The deformation of the delivery sheath705 helps stabilize the position of the sheath 705 in the vasculatureand facilitates accurate deployment of the device 100 to the intendeddelivery site. In contrast, a non-compliant delivery sheath 705 (i.e., asheath that is not deformed to conform to the preformed shape of thedevice 100) maintains a generally cylindrical appearance even throughthe device 100 is stowed within it (FIG. 69C). Regardless of the type ofsheath used, device delivery is accomplished by using the push rod onthe proximal side of the device to fix the position of the device withinthe sheath 705 and then withdrawing the sheath 705 proximally. As thedevice 100 exits the distal end of sheath 705, it assumes the pre-formeddevice shape (FIG. 69D).

The symmetrical device shape (see e.g., devices in FIGS. 15 and 16A),facilitates the deployment and retrieval of the device from multipleaccess points in the vasculature. A device 100 is shown positioned inthe vasculature within the inferior vena cava 11 immediately below therenal veins 13 (FIG. 70). A femoral access path (solid) and a jugular 14access path (phantom) are illustrated. The femoral access path (solid)and a jugular access path may each be used for device deployment,repositioning and retrieval. Alternatively, the vena cava could beaccessed via brachial or antecubital access for device deployment,repositioning and retrieval.

Retrieval of the devices is most preferably accomplished by endoluminalcapture using one of the retrieval features described herein. (i.e.,FIGS. 27A-E) The retrieval features described herein have been designedto work well using a commercially available snares two of which areillustrated in FIG. 71A and FIG. 71B. The single loop gooseneck snare712 is illustrated in FIG. 71 inside of a recovery sheath 710. Themultiple loop Ensnare 714 is illustrated in FIG. 71B inside of arecovery sheath 710. These conventional snares are controlled by aphysician using a flexible, integral wire.

The sequence of device recapture and removal from a body lumen (here thevena caval 1) is illustrated in FIGS. 72A-C. In these figures, the solidlines are for a femoral recovery and the phantom lines are for a jugularrecovery (e.g., FIG. 70). A collapsed snare is advanced via a deliverysheath to the proximity of the retrieval feature 240 (FIG. 72A). Once inplace, the snare 712 is exposed and assumes a pre-defined expanded loopshape which is looped over the retrieval feature 240 as illustrated fromeither end in FIG. 72B.

The snared device 100 can then be either pulled into the sheath 710, oralternatively and more preferably, the recovery sheath 710 is advancedover the device 100 while maintaining positive control of the snare 712as the sheath 710 advances over the device 100. Advancing the recoverysheath 710 over the device 100 facilitates atraumatic removal of thedevice 100 from any tissue that has grown in or around the device 100.The retrieval action, which tends to collapse the device radially inward(FIG. 72D), also facilitates removal from any tissue layer formed on thedevice. Recovering the filtering device by pulling on a flexibleretrieval feature attached to the filtering device. Moreover, pulling ona portion of the filter structure (i.e., a retrieval feature) removesthe opposing spiral elements from the lumen wall.

As the device is drawn into the sheath 710, the pre-formed shape of thedevice also urges the support members away from the lumen wall whichalso assists in atraumatic device removal.

The flexible retrieval element 240 assumes a collapsed configuration asit is being drawn into the recovery sheath as illustrated in FIG. 72Cand FIG. 72E. Note that the retrieval feature 240 on the opposite end ofthe device assumes a straightened configuration as is drawn into therecovery sheath (FIG. 72F). An additional embodiment, in which a singlecurved retrieval feature 140 (FIG. 27A) is withdrawn into the deliverysheath 710 as shown in FIG. 73A. The distal retrieval feature (relativeto the snare) assumes a straightened configuration FIG. 73C from acurved configuration FIG. 73B as is completely withdrawn into the sheathFIG. 73D.

Additionally, repositioning the filter 100 from one lumen position toanother is illustrated in FIGS. 74A-74D. Because of the atraumaticdesign of filter devices of the present invention, repositioning of thefilter device 100 may be accomplished by fully recapturing (FIG. 74C) oronly partially recapturing (FIG. 74B) the device 100 into a recoverysheath 710. The atraumatic design of the device 100 allows the device tosimply secured by one end (FIG. 74B) and pulled along the lumen wallinto the desired position and then released. The delivery sheath andrecovery sheath are provided with the same reference numbers sincefilter devices of the present invention may be deployed into andrecovered from the vasculature using sheaths that are about the samesize. As such, devices of the present invention may be deployed into thevasculature from a delivery sheath having a first diameter. Then, thedevice may be retrieved from the vasculature using a recovery sheathhaving a second diameter no more than 2 Fr larger than the firstdiameter (1 Fr=0.013″=⅓ mm). Alternatively, the second diameter may beno more than 1 Fr larger than the first diameter or, alternatively, thefirst diameter is about the same as the second diameter.

In a full recovery, the device is pulled completely into a recoverysheath (FIG. 74A), the sheath is repositioned from the original position(FIGS. 74A, 74C) to a second position (FIG. 74D) and deployed into thevasculature again (FIG. 69D). In the case where the snare wire columnarstrength is insufficient to redeploy the device, the snare can bedelivered within a secondary inner sheath within the retrieval sheath.This allows the positive control of the retrieval feature to beobtained, such as illustrated in FIG. 74B, the device withdrawn into theretrieval sheath and then redeployed with the inner sheath acting as apush rod.

Various Methods of Using Filtering Devices

Embodiments of filter devices of the present invention may be used inmethods of providing distal protection in procedures such as, forexample, thrombectomy, arthrectomy, stenting, angioplasty and stentgrafting. It is to be appreciated that embodiments of filter devices ofthe present invention may be used in veins and arteries. An exemplaryprocedure is illustrated in FIGS. 75A-I and FIGS. 76A-E. In eachprocedure, the device 100 is positioned in an un-tethered fashionadjacent to the treatment region 730. The sequence FIGS. 75A-Iillustrate the delivery sheath 710 positioning FIG. 75A, completedeployment FIG. 75B into the lumen 10. A conventional treatment device750 using mechanical, electrical energy or other suitable method is usedto clear the undesired material 732 from the lumen wall (FIG. 75C). Somedebris 734 removed from the lumen wall through the use of treatmentdevice 750 is subsequently embolized into the blood stream (FIG. 75C)and trapped by the filter 100 (FIG. 75D). The conventional treatmentdevice 750 is removed (FIG. 75E) and thereafter the advancement ofrecapture sheath 710 is advanced into recovery position (FIG. 75F).

The entrapped debris 734 is then removed prior to recapturing the devicewith methods such as, for example, aspiration, delivery of therapeuticagents or maceration. Additionally, the device and entrapped debris canbe recaptured in whole and removed via the same sheath used to recapturethe device as illustrated in FIG. 75G. The device 100 and debris 734 arethen withdrawn into the sheath 710 (FIG. 75H), and the sheath withdrawnfrom the vasculature (FIG. 75I).

Similarly, an additional use of the invention as un-tethered distalprotection is illustrated in FIGS. 76A-E, in which a balloon 751 is usedto expand the lesion 732 such as in the case of balloon angioplasty,often performed prior to stenting a vessel to keep it open. For thisprocedure a balloon catheter is advanced to the lesion site and inflatedFIG. 76 B, plaque 732 is pushed outward by the balloon (FIG. 76C), thusreestablishing normal blood flow. Any particulate matter 734 embolizedby the procedure is trapped by the filter (FIG. 76D). The debris 734 canthen be removed prior to filter retrieval as previously described or thedevice with trapped debris can be removed together.

An additional method practiced widely in the art is the use of tethereddistal protection adjunctive to the previously described procedures(i.e., the device 100 remains tethered during the procedure).Embodiments of the filtering device of the present invention may also beused for this purpose as illustrated in FIGS. 77A-77E. Positive controlof the filter 100 is maintained via an integral wire or snare connectedto the device 100. The connection between the integral wire or snare tothe device 100 is maintained during the procedure and may be, in someembodiments, used as a guidewire. As illustrated in FIG. 77B, connectionto the device 100 is maintained a while performing a procedure to treatthe vasculature in proximity to the location (i.e, treat the lesion732).

An example of a tethered distal protection method is illustrated inFIGS. 77A-77E. An embodiment of a filter device 100 is deployed distalto the lesion 732 to be treated (FIG. 77A), the treatment is initiated(FIG. 77B), and embolized material 734 is captured in the filter 100(FIG. 77C). Thereafter, the debris 734 is removed prior to filterrecapture or, alternatively, with treatment in the filter 100 via asheath as previously described. The device 100 is recovered into thesheath (FIG. 77D) and removed from the lumen 10 (FIG. 77E).

A tethered device (FIG. 77A, 78A) can also be employed to mechanicallydislodge and remove embolic material 732 from a vessel 10, such as inthe case of a thrombectomy. This offers a simple means of removing andtrapping debris without requiring multiple devices to achieve the samegoal. For this method, the tethered device is advanced downstream of thelesion site (FIG. 78A), and deployed (FIG. 78B). The tethered, deployedfilter 100 is then drawn across the lesion 732 (FIG. 78C) to pull thethrombus from the vessel wall and into the filter 100 (FIG. 78D). Theembolized material 734 is then removed via the methods previouslydescribed (FIG. 78E), tethered device is drawn into the sheath andremoved from the lumen (FIG. 78F).

Delivery of Pharmacological Agents Using Filtering Devices

Embodiments of the filter device of the present invention may also beused for delivering a pharmacological agent within a lumen. Delivery ofthe a pharmacological agent within a lumen may be accomplished using anycomponent of the filtering device. For example, the filter supportstructure may deliver a pharmacological agent. In one alternative, thesupport structure is covered by a multi-lumen structure and themulti-lumen structure is configured to release a pharmacological agent.In one alternative, a lumen of the multi-lumen structure is at leastpartially filled with a pharmacological agent. In another aspect, alumen in a multi-lumen structure has ports that allow for the release ofa pharmacological agent stored within the lumen. In one alternative, acavity formed in a support member is filled with a material. In oneaspect, the material in the cavity is a pharmacological agent. Thefilter may deliver a pharmacological agent. In one aspect the materialcapture structure is coated with a pharmacological agent.

Additional embodiments of the invention provide for the ability todeliver therapeutic agents via the material capture structure as well asthe support structure covering.

FIG. 79 illustrates a therapeutic agent coating 780 attached to afilament 118/461. FIG. 80 illustrates a composite structure 789 formedby having one or more cavities formed in a support structure 105 filledwith one or more therapeutic agents or other material. The cavities maybe formed as described above with regard to FIGS. 33, 35 and 36. Thesecomposite structures can be designed to elute a therapeutic agent via aspecific elution curve by varying thickness, density as well as locationof the therapeutic agent on the filter device component. Thistherapeutic agent could be, for example, any pharmacological agent usedin the treatment of the body, an anti-coagulant coating (i.e., Heparin),an agent prevent or sloe fibrous tissue growth, other agents selectedfrom those used in vascular stents including drug eluting stents.

FIG. 81 and FIG. 82 illustrate the use of the covering 420, 420 apositioned over a support structure as the delivery means for providingpharmacological agents into a lumen. FIG. 81 illustrates apharmacological agent 782 in a lumen 424 a of a multi-lumen structuresuch as described above with regard to FIGS. 44, 45. As illustrated inFIG. 82, the therapeutic agent 784 fills a lumen 424 in a multi-lumencovering 420 a over the support structure 105. Release ports 785 formedin the side of lumen 424 allow delivery of the agent to the blood ortissue. Control of the therapeutic agent elution parameters could becontrolled via the size or spacing of the release ports 785 and/orthrough the use of controlled release pharmacological agents.

Prototype Filtering Devices

FIGS. 83A-83E illustrate perspective (FIG. 83A), plan (FIG. 83B), bottom(FIG. 83C), side (FIG. 83D) and end (FIG. 83E) views of a prototypefilter according to an embodiment of the present invention. Theprototype has previously described features and common elements have thesame reference numbers have been incorporated into these illustrations.The support structure 105, 110 was formed with electropolished 0.013″ ODNitinol wires, shape set to form two substantially equal open loops 126,128 of approximately 1″ diameter. The support structure wire used forsupport structure 105 was ground down to a wire diameter of 0.010″ andused to form flexible retrieval feature 240 on each end (i.e., FIG.28C). An atraumatic feature (here ball 242) is created on the end of thewire by exposing the wire to plasma. A radio opaque marker, here aTantalum marker band 248 attached below the ball 242. The materialcapture structure 115 has filter cells 119 constructed with filaments118. The filaments 118 are 7-0 ePTFE suture. The filaments are attachedto the support structure using method shown in FIG. 47. The cover 185used to join the ends is a tapered Nitinol tube 186 that is crimpedaround the support structures, as illustrated in FIG. 24.

FIGS. 84A-84E illustrate perspective (FIG. 84A), plan (FIG. 84B), bottom(FIG. 84C), side (FIG. 84D) and end (FIG. 84E) views of a prototypefilter according to an embodiment of the present invention. Thisembodiment is similar to the embodiment of FIG. 83A. In this embodiment,the material capture structure 115 is replaced with material capturestructure 312 an made of extruded polymeric netting described above withregard to FIG. 56. This embodiment also illustrates how the supportstructures 105, 110 are not in contact (i.e., separated by a distance“d”) at the crossover 106.

FIGS. 85A-85E illustrate perspective (FIG. 85A), plan (FIG. 85B), side(FIG. 85D) and end (FIG. 85C) views of a prototype filter according toan embodiment of the present invention. This embodiment is similar tothe filter device described in FIG. 14A and common reference numbers areused. In this embodiment, a material capture structure is constructedfrom a continuous sheet of polymeric material 520 into which circularholes 521 are created via mechanical or laser cutting (as describedabove with regard to FIG. 61A).

FIGS. 86A-86D illustrate perspective (FIG. 86A), plan (FIG. 86B), side(FIG. 86D) and end (FIG. 85C) views of a prototype filter according toanother embodiment of the present invention. In this prototype filter, amaterial capture structure constructed from a continuous sheet ofpolymeric material 520 into which a pattern 522 voids are created viamechanical or laser cutting to create a net-like structure (FIG. 61C).

FIG. 87 is a perspective view of a prototype filter according to anembodiment of the present invention similar to the embodiment describedin FIGS. 83A-83E above. In this embodiment the elongate structuralmembers 105, 110 are joined at only one end (i.e., end 102). The supportstructure elements on the unconnected end are finished with plasma balls242 to prevent vessel perforation and facilitate deployment andretrieval.

Summary of Experimental Results

The inventors are currently evaluating the performance of filter deviceembodiments of the present invention. Device performance is currentlybeing evaluated in ongoing in-vivo animal and in-vitro bench studies. Inparticular, several device performance attributes have been evaluated,such as: device loading and advancement within a delivery sheath,deployment accuracy, thrombus capturing ability, fluoroscopicvisibility, positional stability, device durability, and retrieval atthree weeks following implantation. For the animal work completed todate, an ovine animal model has been used, as it is an accepted modelused to study vascular implants, with anatomy and healing responsesimilar to the adult human inferior vena cava (see, e.g., Brountzos E,et. al. “A new optional vena cava filter: retrieval at 12 weeks in ananimal model”, J Vase Intery Radiol. 2003 June; 14(6):763-72; Crochet D,et. al., “Evaluation of the LGM Vena-Tech infrarenal vena cava filter inan ovine venous thromboembolism model”, J Vasc Intery Radiol. 2001 June;12(6):739-45; and Smouse B., “Second-generation optional vena cavafilter” Endovascular Today. 2005 January, 4(1): 64-66, each of which isincorporated herein by reference in its entirety).

To date, thrombus trapping ability of the device has been evaluatedusing an in-vitro model. This model is constructed using segments ofsilicone “mock” vena cava connected to a flow circuit, in which fluid ispumped at approximately 3 L/min and maintained at 20 mm/Hg. Results haveconfirmed device stability and the “wedging” effect illustrated in FIG.16A and FIG. 16B, when subjected to an embolic load that substantiallycovers the filter surface.

Initial animal study feasibility experiments have successfullydemonstrated:

-   -   (a) loading and advancement of devices FIG. 68A in a compliant 6        Fr delivery sheath;    -   (b) compliance and positional stability of the device loaded in        the sheath as shown in FIG. 69B;    -   (c) device visibility using both intravascular ultrasound (IVUS)        and fluoroscopy;    -   (d) deployment accuracy;    -   (e) acute and sub-chronic positional stability;    -   (f) axial distensibility of the device (FIG. 2A-C);    -   (g) ability to acutely capture and reposition device (FIGS.        74A-D) using commercially available snares (FIGS. 71A-B);    -   (h) device durability; and    -   (i) the ability to easily recapture and remove a device after a        three week dwell time using a 6 Fr sheath. The recapture was        performed in less than 3 minutes (FIGS. 72A-F). Recaptured        devices have indicated freedom from significant tissue        incorporation or thrombus formation as well as in-vivo device        durability.

At present, ongoing animal studies will be used to evaluate deviceperformance and retrievability after one and two month implant durations(i.e., vessel dwell times).

It is understood that this disclosure, in many respects, is onlyillustrate of the numerous alternative filtering device embodiments ofthe present invention. Changes may be made in the details, particularlyin matters of shape, size, material and arrangement of various filteringdevice components without exceeding the scope of the various embodimentsof the invention. Those skilled in the art will appreciate that theexemplary embodiments and descriptions thereof are merely illustrativeof the invention as a whole. While several principles of the inventionare made clear in the exemplary embodiments described above, thoseskilled in the art will appreciate that modifications of the structure,arrangement, proportions, elements, materials and methods of use, may beutilized in the practice of the invention, and otherwise, which areparticularly adapted to specific environments and operative requirementswithout departing from the scope of the invention.

We claim:
 1. A method of filtering blood flow in a vena cava,comprising: positioning a collapsed open loop filter support structurecomprising two opposing spiral support elements within the vena cava;deploying the open loop filter support within the vena cava to positiona portion of the filter support along the wall of the vena cava;filtering blood flow in the vena cava using a filter supported by theopen loop filter support structure; and moving the portion of the filtersupport relative to the wall of the vena cava to maintain the shape ofthe filter over a physiological range of the vena cava.
 2. The methodaccording to claim 1 wherein maintaining a position of the open loopfilter support structure within the vena cava is performed withoutpiercing the surface of the lumen.
 3. The method according to claim 1wherein maintaining a position of the open loop filter support structurewithin the vena cava is performed without perforating the lumen.
 4. Themethod according to claim 1 further comprising: applying radial forcegenerated by the open loop filter support structure along the axialdimension of the vena cava.
 5. The method according to claim 1 whereinmaintaining a position of the open loop filter support structure withinthe lumen using radial force generated by the open loop filter supportstructure positions the filter centrally within the vena cava.
 6. Themethod according to claim 1 further comprising: applying radial forcegenerated by the open loop filter support structure around the axialdimension of the vena cava.
 7. The method according to claim 1 furthercomprising: maintaining a nearly constant filtering capacity of thefilter supported by the open loop filter support structure as the sizeof the vena cava changes.
 8. The method according to claim 1 furthercomprising: maintaining the filtering capacity of the filter supportedby the open loop filter support structure over a physiological range ofvena cava sizes.
 9. The method according to claim 1 further comprising:maintaining the filtering capacity of the filter supported by the openloop filter support structure independent of the size of the vena cava.10. The method according to claim 1, wherein the deploying step furthercomprises extending the filter across the flow of the vena cava.
 11. Themethod according to claim 1, wherein moving the portion of the filtersupport relative to the wall of the vena cava comprises sliding theportion of the filter support along the wall of the vena cava.
 12. Themethod according to claim 1, wherein moving the portion of the filtersupport relative to the wall of the vena cava comprises sliding thefilter support against a second filter support.
 13. The method accordingto claim 1, moving the portion of the filter support relative to thewall of the vena cava comprises sliding the filter support relative to asecond filter support without contacting the second filter support. 14.The method of claim 1, wherein after the deploying step, the open loopfilter support lies substantially with an obliquely transverse plane ofthe vena cava.
 15. A method of providing a filter across a lumen flowpath, comprising: providing a filter support structure having a firstend, a second end, and a crossover section between the first end and thesecond end; and positioning the first end against a first portion of thelumen; and positioning the second end against a second portion of thelumen such that the first and the second ends are axially separatedalong the wall on one side of the lumen; positioning the crossoversection against a portion of the lumen between the first and second endsand on a wall substantially opposite to the wall of the lumen supportingthe ends; and using the filter support structure to provide a filteracross the lumen flow path.
 16. The method of claim 15 wherein the endsdo not pierce the lumen surface.
 17. The method of claim 15 furthercomprising fixing the position of the filter support structure withinthe lumen, wherein fixing the position of the filter support structurecomprises fixing the position of the filter support structure within thelumen by positioning the first end against a first portion of the lumenand positioning the second end against a second portion of the lumen andpositioning the crossover section against a portion of the lumen betweenthe first and second portions of the lumen.
 18. The method according toclaim 17 wherein the portion of the lumen between the first and secondportions of the lumen is opposite the first and second portions of thelumen.
 19. The method according to claim 15 further comprising providinganother filter across the lumen flow path.
 20. The method according toclaim 15 further comprising: changing the distance between the crossoversection and the lumen wall opposite the crossover section in response tochanges in the lumen diameter.
 21. The method according to claim 15further comprising: changing the distance between the ends in responseto changes in the lumen diameter.
 22. The method according to claim 15further comprising: delivering a pharmacological agent within the lumenusing the filter support structure.
 23. The method according to claim 15further comprising: delivering a pharmacological agent within the lumenusing the filter.
 24. The method of claim 15, wherein the lumen is avena cava.